The field of the invention is the after treatment of the sulfonation products of non-aromatic hydrocarbon mixtures and the state of the art may be ascertained by reference to West Germany Pat. No. 827,065 and U.S. Pat. No. 4,177,208, the disclosures of which are incorporated herein.
It is known that aliphatic and cycloaliphatic alcohols having at least 5 C atoms in the molecule can be used as extractants to extract the organic components from a crude sulfonation mixture containing unreacted paraffin, water and sulfuric acid besides the desired sulfonic acids, as disclosed in U.S. Pat. No. 4,177,208. In the process, the sulfuric acid separates in the aqueous phase and thus it can be isolated from the alcohol extract. The unreacted paraffin present together with the sulfonic acids remains in the lighter weight organic phase. The entire amount of paraffin present then is separated after neutralization of the sulfonic acids and removal of the extractant from the sulfonic acids present in the form of alkali sulfonates in a further process stage. This process of U.S. Pat. No. 4,177,208 includes the following steps:
(a) admixing with the paraffin sulfonic acid solution, at least one slightly polar alcohol selected from the group consisting of aliphatic and cycloaliphatic alcohols containing at least 5 carbon atoms, having a solubility in water less than 7% by weight which forms an azeotrope with water, thereby forming a mixture having an organic phase containing paraffin sulfonic acids dissolved therein and an aqueous phase containing the sulfuric acid;
(b) separating the organic phase from the aqueous phase;
(c) neutralizing the separated organic phase by admixture with a composition selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal carbonates thereby converting the sulfonic acids present in the organic phase into sulfonates, and forming a neutralized organic phase wherein the ratio of the amount of water to the amount of slightly polar alcohol in the neutralized phase is at most equal to the corresponding ratio for the azeotrope which forms between water and the slightly polar alcohol; and
(d) removing the volatile components from the neutralized organic phase to recover the sulfonates under temperature and pressure conditions whereby the sulfonates are in a molten state.
It is furthermore known from West German Pat. No. 827,065 to purify and concentrate alkali sulfonates of high-molecular aliphatic hydrocarbons by extracting their aqueous solutions. Such solutions are obtained by treating the industrial saponification products of corresponding higher-molecular aliphatic hydrocarbon-sulfochlorides with a mineral acid, with higher alcohols or their mixtures only slightly soluble in water or not at all soluble and be treating thereupon the alcohol solution sequentially with water and alkali liquor.
Higher aliphatic or aromatic alcohols are suitable for the extraction, preferably such hydroaromatic alcohols as cyclohexanol and methylcyclohexanol. Contrary to what is the case for the process disclosed in U.S. Pat. No. 4,177,208, the process of the German Pat. No. 827,065 calls for removing the unreacted paraffin in a separate process stage prior to the treatment with the alcohol.
Thus, according to both processes of the prior art, the unreacted paraffin and the sulfuric acid obtained as a by-product (in the case of the sulfoxidation) or the chlorides (in the case of the sulfochlorination) are removed from the sulfonation mixture in two separate process stages.